1. Field of the Invention
The present invention relates to welding rods, and more particularly, to uncoated triangular metal alloy welding rods having a uniquely configured channel shaped lower section.
2. Description of the Prior Art
Heli-arc welding systems utilize a shield of argon gas to block out the ambient atmosphere at the welding point to substantially reduce contamination of the welded seam. The ends of steel pipes or steel plates which are joined together by heli-arc welds generally have 37.5 degree bevelled ends. Prior to commencing the welding operation, the steel plates or steel pipes are carefully aligned and positioned with about a 1/8 inch gap between the adjacent sections of the bevelled ends.
The initial stage of the welding process involves forming a first pass or stringer bead in which one part of the welded seam must bridge the gap between the surfaces of the bevelled ends of the two elements to be joined together while another portion of the seam must join together the inside surfaces of the pipes or steel plates. The penetration of the welded bead onto both sides of the aligned ends of the steel pipes or steel plates is essential to form a perfect weld. The primary problem in the heli-arc welding technology is that the precisely required stringer bead penetration cannot be uniformly attained.
Welders using present day heli-arc welding techniques almost exclusively use round welding rods to form the stringer bead in the V-shaped groove formed by the bevelled ends of adjacent steel plates or steel pipes. Since the circular cross section of the round welding rod and the V-shape of the groove are geometrically incompatible, it is extremely difficult to form a perfect welded seam and often as many as 40% of the finished welds fail to pass inspection. When a weld fails to pass inspection, the welded junction must be cut out and redone at substantial cost.
U.S. Pat. No. 3,999,035 (Miyal) discloses numerous types of arc welding electrodes having various geometric configurations for the flux coated welding rods. Column 5 and FIGS. 8C and 8D of this patent disclose a triangular shaped, flux coated welding electrode.
U.S. Pat. No. 3,515,846 (Nakamura) discloses a multilayered arc welding electrode having a generally triangular cross section. As illustrated in FIGS. 6 and 7, the Nakamura arc welding electrode is positioned within a groove between two metal plates and has length and width dimensions approximately equal to the dimensions of the groove to be welded.
U.S. Pat. No. 2,410,461 (Ronay) discloses a multi-layered, hollow core arc welding electrode. U.S. Pat. No. 2,148,182 (Applegate) discloses a generally triangular shaped arc welding electrode having a strip of inorganic material coupled to the rear surface thereof which is intended to fit snugly within a corner well where the welded seam is to be placed. The strip of inorganic material shields the arc and confines it to the region of the weld. Metal splatter is thus avoided and the weld metal is uniformly distributed in the corner of the joint.
The following U.S. Pat. Nos. disclose various other types of welding electrodes: 1,788,310 (Lebrun et al); 3,114,033 (Elster et al); 2,785,285 (Bernard); 2,042,899 (Howland) and 3,043,946 (Perrin).